Growing Grapes in WV - West Virginia Department of Agriculture

are wormy at harvest time. It is adark-colored caterpillar. It passesthe winter in the pupal stage onfallen leaves. It emerges about thetime the grapes are blossoming.There are two broods. The first eatsthe stems and external portions ofthe young berries. The caterpillarsof the second brood live entirely inthe berries. They attack all cultivars.They are most injurious to thosecultivars that have compact clusterssince they tend to be protected insuch clusters and can feed readilyon more than one berry. Someof the injured grapes fall from theclusters; the rest must be discardedat harvest time. Spraying is the bestcontrol, but deep cultivation of theleaves in late fall or early springalso aids in control. For a few vines,it often pays to pick and destroy theberries infested by the spring broodand to rake and burn the leaves inthe fall to reduce the overwinteringpopulation. Populations may bemonitored with a commercially availablepheromone trap. Trichogramaminutum Riley is an egg parasitethat will provide some biologicalcontrol.The rose chafer (Macrodactylussubspinosus (Fabricius)) may bevery bad in some seasons, especiallywhere there is light, sandysoil nearby. It is a long-legged,yellowish-brown beetle about onethirdinch long. It may appear in vastswarms about the middle of June orearlier. It stays about a month andeats foliage of all kinds in gardens,vineyards and orchards. The larvaefeed on the roots of grasses in sandysoil. Consequently, if most of thesurrounding land is under cultivation,the number of chafers may bekept down. Cultivation also destroys-20-some of the pupae. Petal-fallsprays for grape berry moth willalso control rose chafers.The Japanese beetle(Popillia japonica (Newman))is a shiny metallic-green beetleless than half an inch long withcoppery-brown front wings. It isof considerable importance inparts of West Virginia. It usuallyappears between June 1 and 15,and may be present until mid-August or later. Grape leavesare among its favorite foods, andunless protected many of theleaves may be reduced to a lacelikeskeleton. The eggs are laid inthe soil in grassy areas and thegrubs develop there. The larvaemay be controlled by a bacterium,Bacillus popillae (milkyspore). This biological controlagent is applied to grassy areasto control large larval populations,but is not effective againstadults. Commercially availableattractant traps are generally notadequate to protect vineyards,but can be useful in monitoringpopulations. Insecticide applicationswill usually be necessary forcontrol of the adults.The Grape root borer(Vitacea polistiformis (Harris))can cause extensive damage toa vineyard before its presence iseven detected. Although inconspicuous,the larval feeding canresult in yield losses and deathof the vines. The borers, whichare white with brown heads andrange in size from less than aninch to two inches, feed beneaththe outer bark of the roots. Theadults, unlike most moths, flyonly during the day, and often escapeidentification because they